Reorganization of jaw muscle activity during experimental jaw muscle pain

Background and Aims: Temporomandibular disorders are clinical conditions that often involve pain in the masticatory muscles, the temporomandibular jaw joint and/or associated structures. The association between muscle pain and muscle activity is often explained by uniform increases or decreases in motor unit activity throughout a muscle but recent evidence suggests more complex changes within a painful muscle. The general aim of this study was to determine if experimentally induced masseter muscle pain modifies temporalis muscle activity. Methods: 20 healthy participants received experimental pain through hypertonic saline (5% NaCl) infusion into the right masseter; pain intensity was maintained at 40-60/100 mm on a visual analogue scale (VAS). Standardized biting tasks were performed with an intraoral force transducer while single motor unit (SMU) activity was recorded from 2 intramuscular electrodes (right masseter and right temporalis). The tasks were repeated in 4 blocks: baseline 1, hypertonic saline infusion, isotonic saline infusion, baseline 2. Each block had 3 isometric biting tasks: a slow and a fast ramp jaw closing task and a 2 step-levels jaw closing task (2 force levels: step 1 and step 2). Results: 83 SMUs were discriminated from the temporalis and 58 from the masseter muscle. This study demonstrated that induced muscle pain in the right masseter can be associated with the activation of new SMUs and the silencing of other single motor units in the painful masseter muscle as well as in the right temporalis muscle, which did not receive noxious stimulation with the hypertonic saline. No differences between pain and no pain trials were found in thresholds and firing rates of SMUs from the temporalis muscle. Discussion and conclusion: The present findings are consistent with previous findings from the limb (Hodges and Tucker 2011; Tucker et al. 2009) and rather than supporting uniform increases or decreases in motor unit activity throughout a muscle, suggest that there is a reorganization of motor unit activity across the entire jaw motor system in experimental pain

Analysis of Facial Skin Temperature Changes in Acquaintance Comparison Question Test

From introduction: "Polygraph instruments have been used in criminal investigations for a long time now, and several types of tests using the polygraph have been developed. One such test is called the Acquaintance Comparison Question Test (ACQT) [1], which is extremely effective when traditional polygraph measures are used. However, the devices used to record these measures still resemble the fi rst models from 20 years ago [2, 3] and most often include metal electrodes attached to the fingers, pneumatic tubes surrounding the thoracic and abdominal areas, and a pneumatic blood pressure cuff attached to the upper arm overlying the brachial artery. Th ese sensors require time to attach, and the examinee can feel certain discomfort when the blood pressure cuff is infl ated for more than approximately fi ve minutes. Additionally, the autonomic nervous system (ANS) measures of the orienting response rely on such cognitive phenomena as memory updating rather than emotional responses to the test questions [4–7]. Many believe that increases in polygraph accuracy might be possible if questions could be determined. Th is would be useful not only in the ACQT format, but in other polygraph test formats as well. Research has documented a link between behavioral reactions and the expression of specific emotions [8–11]. Th e cited studies typically involve detailed measures of facial muscles as specifi c emotions are invoked. One technology that shows promise in overcoming some of the limitations of traditional polygraph measurements is thermography."(...

Automatic Facial Expression Recognition and Operator Functional State

The prevalence of human error in safety-critical occupations remains a major challenge to mission success despite increasing automation in control processes. Although various methods have been proposed to prevent incidences of human error, none of these have been developed to employ the detection and regulation of Operator Functional State (OFS), or the optimal condition of the operator while performing a task, in work environments due to drawbacks such as obtrusiveness and impracticality. A video-based system with the ability to infer an individual's emotional state from facial feature patterning mitigates some of the problems associated with other methods of detecting OFS, like obtrusiveness and impracticality in integration with the mission environment. This paper explores the utility of facial expression recognition as a technology for inferring OFS by first expounding on the intricacies of OFS and the scientific background behind emotion and its relationship with an individual's state. Then, descriptions of the feedback loop and the emotion protocols proposed for the facial recognition program are explained. A basic version of the facial expression recognition program uses Haar classifiers and OpenCV libraries to automatically locate key facial landmarks during a live video stream. Various methods of creating facial expression recognition software are reviewed to guide future extensions of the program. The paper concludes with an examination of the steps necessary in the research of emotion and recommendations for the creation of an automatic facial expression recognition program for use in real-time, safety-critical missions

Functional evaluation of skeletal muscle regeneration following severe crush trauma and the therapeutic application of specialized tissue engineering in the rat

Introduction: Skeletal muscle trauma is a common condition which may result in long term pain and disability. Despite the pool of muscle-specific stem cells termed satellite cells, which are stimulated to proliferate, grow and differentiate to repair muscle fibers upon injury, return to pre-injury function is often impossible. We hypothesized that the transplantation of Mesenchymal Stromal Cells (MSCs) in a synthetic niche supplemented by stimulatory growth factors may support the regenerative process through paracrine modulation of the post-traumatic microcellular environment Methods: A crushed-muscle injury model was implemented in rats. Upon completion, rats received either intramuscular Injections of the growth factors (GF) Insulin Growth Factor-1 and Vascular Endothelial Growth Factor and/or autologous MSCs which had previously been harvested in a bone marrow aspiration, or a specially engineered porous Alginate enriched with the before mentioned growth factors and/or seeded with MSCs. Animals were sacrificed at 7-, 28- and 56 days following trauma and their fast twitch- and tetanic contraction forces were measured via an electromechanical stimulatory device. Results: All experimental groups showed significant decreases in contraction strength at day 7 following injury, with little difference amongst groups. On the contrary, fast twitch and tetanic contraction forces differed significantly between the Alginate-alone control group and the groups transplanted with with Alginates seeded with MSCs and Alginates enriched with GFs and seeded with MSCs at day 28. The highest relative force was found in the latter group, which differed significantly from the others (p (Alginate) <0.001; p (Alginate + GFs) = 0.003). No significant increases in muscle force could be observed in between the groups evaluated at 28 days following trauma and the groups evaluated at 56 days following trauma. Conclusion: We could confirm that the transplantation of a porous Alginate enriched with growth factors and seeded with autologous Mesenchymal Stromal Cells resulted in significantly improved functional outcomes. Tissue engineering, which relies on the transplantation of cells and growth factors conducive of regeneration seeded on scaffolds which support their survival and release into the microcellular environment, may be a solution in particular to nosocomial damage created by incisions necessary during a surgical procedure.Einleitung: Schwere Skelettmuskeltraumata sind ein häufiges klinisches Problem was zu langfristigen Schmerzen und eingeschränkter Mobilität führen kann. Trotz des Pools an muskelspezifischen Stammzellen, die als Satellitenzellen bezeichnet werden, die zur Proliferation, zum Wachstum und zur Differenzierung stimuliert werden, um Muskelfasern nach einer Verletzung zu reparieren, ist die Rückkehr zur Vorverletzungsfunktion oft unmöglich. Wir stellten die Hypothese auf, dass die Transplantation von mesenchymalen Stromalzellen in einem flexiblen Konstrukt, ergänzt durch stimulierende Wachstumsfaktoren, den regenerativen Prozess durch parakrine Modulation der posttraumatischen Mikrozellularumgebung unterstützen kann. Methodik: Es wurde Ratten ein Quetschtrauma des Skelettmuskels zugefügt. Posttraumatisch erhielten die Ratten entweder intramuskuläre Injektionen der Wachstumsfaktoren Insulin- Wachstumsfaktor-1 und des vaskulär-endothelialem Wachstumsfaktors und / oder autologe mesenchymale Stromalzellen, die zuvor in einer Knochenmarkaspiration gewonnen worden waren, oder ein speziell konstruiertes poröses Alginat, angereichert mit den eben genannten Wachstumsfaktoren und / oder mit mesenchymalen Stromalzellen. Die fast twitch sowie die tetanische Kontraktionskraft der Tiere wurden an den Tagen 7, 28 und 56 nach dem Trauma mittels einer elektromechanischen Stimulationsvorrichtung gemessen. Ergebnisse: Alle Versuchsgruppen zeigten am Tag 7 nach der Verletzung eine signifikante Abnahme der Kontraktionskraft, mit geringen Unterschieden zwischen den einzelnen Gruppen. Im Gegensatz dazu unterschieden sich die Kontraktionskräfte zwischen der Kontrollgruppe, der leere Alginate transplantiert wurden, und der mit Wachstumsfaktoren und/oder Stromalzellen bereichterten Alginaten transplantierten Gruppen am Tag 28 nach der Verletzung signifikant. Die höchste Kraft wurde in der Versuchsgruppe gefunden, in der Alginate mit Wachtumsfaktoren und mesenchymalen Stammzellen transplantiert wurden, gefunden. Sie hob sich signifikant von den anderen ab (p (Alginat) <0,001; p (Alginat + GF) = 0,003). Zwischen den Versuchsgruppen, die 28 Tage nach dem Trauma ausgewertet wurden, und den Gruppen, die 56 Tage nach dem Trauma ausgewertet wurden, konnte keine signifikante Zunahme der Muskelkraft beobachtet werden. Schlussfolgerung: Wir konnten bestätigen, dass die Transplantation eines mit Wachstumsfaktoren angereicherten und mit autologen mesenchymalen Stammzellen besetzten porösen Alginats zu signifikant verbesserten funktionellen Ergebnissen führt. Spezialisiertes Tissue Engineering, das auf der Transplantation von Zellen und wachstumsfördernden Faktoren beruht die mittels eines flexiblen Biomaterials transplantiert werden können, dürfte eventuell eine Lösung für nosokomiale Muskelschäden sein, die während eines chirurgischen Eingriffs entstehen können